Earth Science Regents Review Unit 3

What are the layers of the earth? Crust: thin, rocky outer layer (oceanic and continental) Lithosphere: crust and upper part of the mantle. Asthenosphere: top part of the mantle, convection occurs within

Facts About the Layers Mantle: thickest middle layer, mafic, crust dives into the mantle to melt Outer Core: made of iron and nickel, solid Inner Core: made of iron and nickel, liquid

2) What are the different types of crust and how do they differ? Continental crust: land crust, lighter, less dense, granite, thicker Oceanic crust: under the ocean, darker, more dense, basalt, thinner

4) Is the outer core solid or liquid? How can you tell? Liquid; The interior temperature is above the melting point.

Summary: 2,000 km 3 mill atm Outer core Stiffer mantle A) At what depth is the temperature 4,200oC ____________ Layer? ______________ B) What is the pressure at a depth of 5,000 km ____________ 2,000 km Stiffer mantle 3 mill atm Outer core

What are the three types of plate boundaries? A) convergent B) divergent C) transform

2) What are divergent boundaries? Type: Divergent (plates move apart) Geologic Feature: Mid-ocean ridges Example: Mid-Atlantic Ridge midocean ridge rift valley

Convergent Boundaries mountains Type: Continent-Continent convergence (plates move together) Geologic Feature: Mountains Example: Himalayas

Convergent Boundaries Type: Continent-Oceanic convergence Oceanic crusts sinks into the mantle and melts (subduction) Geologic Feature: Volcanic Mountains and Trenches Example: Andes Mountains & Peru-Chile Trench volcanic mts. trench

Convergent Boundaries volcanic islands trench Type: Oceanic-Oceanic convergence (two oceanic plates come together) Geologic Feature: Volcanic Islands and deep trenches Example: Aleutian Islands, Aleutian Trench

Transform Boundaries Type: Transform (plates slide past each other) Geologic Feature: Faults Example: San Andreas Fault

How do you use p. 5 of the ESRT’s? Aleutian Isl. Himalayas Andes Mts.

2) What evidence is there for past crustal movement? folding faulting tilting

Who was Alfred L. Wegener? He proposed that the earth was a single supercontinent (Pangaea) that separated over time.

What evidence did he have for his theory? N. and S. America fit together with Africa and Europe The structure of the rocks matched perfectly with the coast of Africa and Europe Tropical fossils were found in cold climates along the coast Evidence of glaciation in S. America, S. Africa, India & S. Australia

3) What do we know about the age of the ocean floor? New crust is created at ridges so the oldest crust is near the continents.

5) What happened to the earth’s magnetic field? Periodically, the poles switch positions and the north pole becomes the south pole (reverse polarity).

6) How do we know this happened? The rocks of the ocean floor contain iron and their magnetic orientation keeps switching.

2) What are the two types of waves? Primary waves (P-waves): compressional waves, faster, go through anything Secondary waves (S-waves): shear waves, slower, can only go through solids

3) What is a shadow zone? This is an area of the earth where earthquake waves cannot be detected.

4) How is it created? (a) S-waves can only go through solids so they get absorbed when they reach the outer core. (b) P-waves get refracted when they reach the outer core.

How do we find the epicenter distance of one wave? Locate the travel time along the y-axis Go across until you hit the curve Look down to see where they meet

5) How do we find the epicenter? Using p. 11 of the ESRT’s find the travel time, go across to the P or S curve then look straight down. Every line = 20 sec Every line = 200 km

1) What does information from seismograph stations tell us? One station? Distance to the epicenter.

1) What does information from seismograph stations tell us? Two stations= two possible locations Three stations= the exact geographic location

2) What happens as the two waves travel farther away from the epicenter? The two waves get farther apart because the P-wave is much faster.

Finding the epicenter distance using two waves? Draw two dots on a paper the number of minutes apart. Slide the paper until the dots match the curves. Look down to see the distance.

Can we answer these? 2,800 km 4,800 km 3,000 km 8,000 km If the travel time of an S-wave is 9 minutes 40 seconds, what is the epicenter distance?______________ If the difference in arrival times of the P- and S-waves is 6 minutes 20 seconds, how far is the distance to the epicenter? ________________ A P-wave arrived at 3:32:00 p.m. and the S-wave arrived at 3:36:30 p.m. How far away is the epicenter?_____________ If a P-wave arrived at 12:02:50 p.m. and the S-wave arrived at 12:12:10 p.m., what is the distance to the epicenter? ________________ 2,800 km 4,800 km 3,000 km 8,000 km

-Match each lettered location with the correct seismogram Exit Card -Match each lettered location with the correct seismogram -If the difference in arrival times of the P- and S-waves is 5 minutes 00 seconds, how far is the station from the epicenter? A D B C 3,600 km